The BSE benchmark Sensex gained over 300 points in the afternoon trade. It was trading at 19,828, up by over 307 points a short while ago. Analysts said the gain in sensex is due to sustained buying by funds and retail investors, buoyed by improved domestic economic growth. Hong Kong's Hang Seng Index was down by 0.54 per cent, while Japan's Nikkei Index lost 0.11 per cent in early trade. In the US, the Dow Jones Industrial Index ended 0.42 per cent lower yesterday.